The accuracy and clinical significance of ultrasound biomicroscopy observing zonule situation / 中华实验眼科杂志

Background The situation of zonule is very important for determining the cataract surgery.Ultrasound biomicroscopy (UBM) is an important method to observe the situation of zonule before cataract surgery.Objective This study was to evaluate the accuracy and clinical significance of observing the zonule of cataract patients by UBM.Methods A series cases-observational study was performed.One hundred and thirty eyes of 130 cataract patients who were to receive extracapsular cataract enucleation were enrolled in Tianjin Eye Hospital from January to June 2015,including 59 eyes with cataract associated with primary angle-closure glaucoma (PACG) and 71 eyes with traumatic cataract.UBM examination was carried out before surgery,and the abnormalities of zonule were recorded and compared between UBM and surgery findings.This study was approved by the Ethic Committee of Tianjin Eye Hospital and informed consent was obtained from all subjects.Results A large space between lens and cilliary was exhibited and the echo of zonule was clear on the UBM image in the eyes with traumatic cataract.The typical anatomic findings of the anterior eye segment were displayed,and lens equator came into contact with cilliary on the UBM image,and the echo of zonule was blurry in the eyes with cataract associated with PACG.The eye number of abnormal zonule was consistent between UBM and surgery findings (Kappa=O.952),and no significant difference in the eye number of abnormal zonule between UBM and surgery findings (P =0.250).In 75 zonule abnormal eyes diagnosed by both UBM and surgery findings,zonule abnormal range could not be compared in 1 eye (1/130,0.77％),and exactly consistent in 8 eyes (8/130,6.15％) between the two methods.The difference of zonule abnormal range between the two methods was 1 clock in 35 eyes (35/130,26.92％),and 2 clock in 27 eyes (27/130,20.77％),3 clock in 4 eyes (4/130,3.08％).In 74 zonule abnormal eyes,the mean difference of zonule abnormal meridian between the two methods was (1.36 ± 1.29) clock,an those in 28 traumatic cataract eyes and 36 cataract with PACG eyes were (1.14±1.10) clock and (1.64-± 1.48) clock,respectively.Conclusions UBM is able to observe zonule accurately,the observation effectiveness of UBM for traumatic cataract is better than that of cataract combined with PACG.These results are of clinical valueable for surgical strategy of cataract and prediction of surgical complications.

A Case of Long Anterior Lens Zonule and Pigment Dispersion Syndrome

PURPOSE: To report a case of long anterior lens zonule and pigment dispersion syndrome. CASE SUMMARY: A 67-year-old female visited our clinic with complaint of visual disturbance in the left eye. She had no history of nyctalopia. Visual acuity was 0.6 in the right eye and 0.4 in the left eye. Intraocular pressure was 12 mm Hg in the right eye and 16 mm Hg in the left eye. Nuclear sclerosis was observed in the left lens. There was no pseudoexfoliative material observed. In the left eye, long anterior zonules with brown pigmented lens striae were spotted irregularly in every direction of the anterior lens. On gonioscopy, the angle was open, and dense, uniform, trabecular meshwork pigmentations were observed at the interior 120 degrees. On fundus examination, cup-to-disc ratio was 0.4 in the right eye, 0.3 in the left eye, and multiple hard exudates were observed in both retinas. Axial length was 22.03 mm in the right eye and 21.84 in the left eye. Anterior chamber depth was 2.71 mm in the right eye and 2.47 mm in the left eye. Defects in the retinal nerve fiber or visual field examination were not observed and pigment dispersion syndrome was diagnosed. The patient showed no significant change at the 9-month follow-up. CONCLUSIONS: We diagnosed atypical pigment dispersion syndrome associated with long anterior zonules and pigmented lens striae. Late onset retinal degeneration should be ruled out with chromosomal analysis if patients show nyctalopia, retinal pigment epithelium atrophy, or family history.

A novel concept of accommodation:Human eyes optical system based on hyperfocal distance-micro zoom / 中华实验眼科杂志

Based on a concept of the hyperfocal distance from photographic lens,this study proposes that emmetropia presents far-hyperfocal distance,near-hyperfocal distance and accommodative hyperfocal distance.When emmetropic presbyopias completely lose the ability of accommodation,its farthest blur point is not beyond 1.5 m,even not being at infinity,and the phenomenon of dark focus both completely match with the definition of hyperfocal distance.On the other hand,after cycloplegic mydriatics in emmetropia,it could be found in the region of depth-of-field that there is no change in the back depth of field (clearness in far vision),but change was found in the front depth of field (blur in near vision).It conforms well to the definition of the hyperfocal distance,demonstrating that human eyes belong to the hyperfocal distance optical system.Furthermore,it is reported that the emmetropic presbyopias rarely matched the spectacles higher than +2.50 D in their whole life;therefore,it can be inferred that their accommodative amplitude in youth is equal to this corrected value.This value accounts for about 4％ of the total refractive power in human eyes,so it is suggested that human eye is a micro zoom optical system.Based on the objective existence of hyperfocal distance,the author proposes that human eye is an integrated accommodative mechanism.It includes three components:the accommodative mechanism of near vision,the measuring and controlling mechanism of near vision,and the general control of near vision.This paper discusses the accommodative mechanism of near vision and the resting mechanism of distance vision based on the hyperfocal distance,and considers that when human eye transfer into the accommodation of near vision from the normal distance vision of hyperfocal distance.There are three different pushing forces contributing to lens deformation and its anterior shift,and these forces cause four different accommodative efforts,which constitute the real accommodative efforts in the relative tissue.This paper also points out that it is only the mode of pushing accommodation that can make the lens vary refraction quickly and greatly,and control the amount of deformation effectively.That can not be achieved by the stretching mode proposed by Tscherning & Schachar,because some authors have verified that excessive pulling would result in decline in the refraction,which would be difficult to regulate and control the eye.Similarly,the self-bulging mode of Helmholtz & Gullstrand will not work neither,because it is unable to control the amount of lens deformation that is its fatal defect.

A brief talk on ‘ A novel concept of accommodation : Human eyes optical system based on hyperfocal distance-micro zoom ' / 中华实验眼科杂志

Accommodation is a phenomenon that crystalline lens change its refractive power when human eyes see the near objects clearly.The article of A brief talk on ‘ A novel concept of accommodation:Human eyes optical system based on hyperfocal distance-micro zoom'.written by Luo Fu-ming introduces a concept of hyperfocal distance from the camera.Based on the characteristic of hyperfocal distance,the author proposes that there are actually three kinds of hyperfocal distances in human eyes:far-hyperfocal distance,near-hyperfocal distance and accommodative hyperfocal distance.It is important to understand this article that whether the ciliary muscles contract to push the zonules in accommodation,and then the zonules are forced to push the lens equator,or the ciliary muscles contract to relax the tensional zonules,then the posterior surface of the lens moves forward.In view of the anatomic structure,the possibility that the ciliary muscles contract to push the zonule and then the slim zonules push the lens equator is less than that the ciliary muscles contract to relax the tensional zonules and then the posterior surface of the lens moves forward in accommodation.In my opinion,the contraction of the ciliary muscles would startup actively in accommodation.So when the eyes transfer from near vision to distance vision,the ciliary muscles (contracting circular muscles) will return to the relaxed normal state immediately.The crystalline lens will immediately recover to its original relatively flatten state by traction of the zonules,rather than passive compression.Because the crystalline lens is not the startup body but a supporting body in accommodation.The accommodation of human eye is very complicated.During the whole process of accommodation,there are not only contraction of ciliary muscles and increase of refractive power in crystalline lens,but also accompanied reaction of miosis and convergence.So it is difficult to explain the complex activity of human eyes using any extreme,mechanical and single mode.

Ultrastructure changes of lens zonule in experimental myopia induced by eye lid suture / 第二军医大学学报

Objective:To observe the lens zonule infrastructure changes in experimental myopia. Methods; The eye lids were sutured to induce the myopia in guinea pigs and the zonule ultrastructure changes were observed. Results: There were significant differences in the eye axial length and diopter between lid-sutured eyes and controls(P

Assessment of zonules after blunt trauma using ultrasound biomicroscopy / 中华超声影像学杂志

Objective To evaluate the role of ultrasound biomicroscopy(UBM) as a method for assessing the zonules after eye blunt trauma,in order to help the selection of the surgical technique and improve the outcomes of traumatic cataract surgery.Methods Two hundred and seven eyes with eye blunt trauma were examed using UBM with a 50 MHz transducer.The degree and extent of the zonular defects were recorded.All patients also had the slit-lamp examination before the UBM.Results Examined using UBM,zonular defects were identified in 67 of 207 eyes(32.4%).Zonular abnormalities include broken zonules and stretched zonules.Forty-six eyes(68.7%) had broken zonules,15 eyes(22.4%) had stretched zonules,6 eyes(9.0%) had both broken and stretched zonules.The extent of broken zonules ranged from under one quadrant to 360?.Increased lenticular sphericity and ciliary body flattening were seen in the area of zonular defects on UBM.Examined using slit-lamp,35 of 207 eyes(16.9%) had phacodonesis and iridodonesis.Conclusions UBM is an effective method for identifying zonular defects in patients with anterior segment trauma.Diagnosing zonular defects preoperatively is of helpful in surgical planning and reduce complications.

Lens Dislocation during Extracapsular Cataract Extraction in Exfoliation Syndrome: A Case Report

The authors present a case of lens dislocation during planned extracapsular lens extraction in a 80-year-old man with exfoliation syndrome. The other eye underwent intracapsular lens extraction without complications such as lens dislocation or vitreous loss. In review of literatures the cause of lens dislocation is due to increased fragility of zonule in exfoliation syndrome.